Actually, part of my question is whether you can in "real life". It was suggested that if you do that, it's some other verb, like "declare candidacy" but not nominate.
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NickCFeb 9 '12 at 0:28

You can still say nominate. To nominate yourself as a candidate would be to put your name down as a candidate whereas to declare candidacy would be to announce that you will be a candidate. You can say nominate or declare candidacy since the latter implies that the candidate was nominated (as you would be in order to become a candidate). e.g. 'She announced her candidacy'. (Well we know that she's been nominated by either herself or someone else.) You can definitely use nominate but you can also describe effectively the same thing in other ways e.g., 'declare candidacy'.
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RachelFeb 9 '12 at 4:02